As packet services and intelligent terminals develop quickly, a high-speed service with a large data volume has an increasingly high requirement on spectrums. According to the latest released FCC International Spectrum White Paper, unlicensed and license-free spectrum resources are more than licensed spectrum resources. An unlicensed spectrum includes frequency bands used for industrial, scientific and medical (ISM) devices and the like. For example, there are three frequency bands in the United States: 902 MHz to 928 MHz, 2400 MHz to 2484.5 MHz, and 5725 MHz to 5850 MHz, where 2.4 GHz is a common ISM frequency band of various countries.
The Long Term Evolution system (LTE) of the 3rd Generation Partnership Project (3GPP) can effectively use unlicensed spectrum resources, and increase available spectrum bandwidths for LTE users. Therefore, it is suggested that LTE is widely applied to unlicensed spectrums. In addition to use of the ISM frequency band, in LTE, a licensed frequency band may also be shared in an authorized shared access (ASA; or LSA, licensed shared access) manner, for example, television white space (TVWS) is used. In this case, a priority of an authorized user is higher than that of a secondary user, that is, an unauthorized user sharing the licensed frequency band.
In an application, LTE needs to detect whether a device, for example, a radar, is using an unlicensed spectrum. Once detecting that a device, for example, a radar, is using the unlicensed spectrum, LTE needs to stop sending information on the unlicensed spectrum, and switch to an available unlicensed spectrum. Because a signal of the device, for example, a radar, may be random and dynamic, handover between unlicensed spectrums also needs to be dynamic.
Existing handover between spectrums is static or semi-static, which cannot meet the requirement of dynamic handover in LTE. In addition, a user data interruption is caused in a handover process, affecting the user experience.